Swimming pools typically include outlet fittings located beneath the surface of the water on the pool interior. These fittings supply the outgoing flow of water to the pool circulation system. Under certain circumstances, such fittings can entrap a bather with their suction, resulting in serious and sometimes fatal physical injury or death by drowning.
Swimming pools subject to these suction entrapment hazards have outlet fittings which are in direct fluid communication with centrifugal circulation pumps. These pumps are capable of creating dangerously high vacuum levels when water supply is restricted or blocked. This can occur when a bather blocks the flow of water through the outlet fitting. The flow blockage which results causes the centrifugal circulation pump to create a high vacuum level within the piping attached to the outlet fitting entrapping the bather.
To prevent these hazards in new swimming pools, new building codes and regulations are being enacted which require multiple outlet fittings for each swimming pool centrifugal circulation pump. However, multiple outlet fittings can not prevent injuries if alternate fittings are blocked by debris or by another bather, or a low water level shut-off valve is closed. In any case, adding additional outlet fittings to existing swimming pools is often impractical or impossible.
In an alternative attempt to prevent suction related injuries, covers for outlet fittings have been designed and commercialized in which, the geometrical orientation of their orifices, the flow therethrough from being totally blocked by a human body. Unfortunately, these protective covers must be removable to facilitate construction and maintenance of the pool. Consequentially such covers are frequently broken or missing in an operational swimming pool. Thus the protection afforded against bodily suction entrapment can be somewhat illusory.
Certain valves shut off the flow at the outlet fitting if the safety cover is missing. However, such valve are specifically designed for a particular outlet fitting model. Not all outlet fittings accept such valves.
In addition to suction entrapment safety devices installed at the outlet fittings, described above, protective safety devices have been designed that can be also installed on the circulation system to minimize the risk of suction entrapment injury. One such device is an electrical switch that shuts off the circulation pump in the event the vacuum level within the piping reaches a dangerous level. However, if the circulation system incorporates a check valve (e.g., a one way valve), stopping the circulation pump does not always neutralize the vacuum level and free the entrapped bather.
Additionally, safety relief valves have been designed to react to the dangerously high level of vacuum within the circulation system piping that accompanies the suction entrapment of a bather, and by their actuation, neutralize this vacuum with the introduction of atmosphere. These safety relief valves are attached to and in fluid communication with the piping near the pump. These devices offer a convenient and easily installed solution to these hazards on existing swimming pools.
Such safety relief valves incorporate a similar irresolute process of opening. They open by atmospheric pressure overcoming the pressure provided by a spring against a movable plug when the vacuum within the piping increases. Normally the spring holds the plug in the closed position. When the vacuum increases above the safe level the atmospheric pressure overcomes the spring and pushes the plug so as to open the valve to atmosphere. The problem with this method is that when the vacuum level approaches the predetermined desired actuation point the valve position can vacillate between closed and open. Such valves may even repeatedly open partially and reclose, not achieving full actuation unless the desired actuation point has been exceeded by a substantial margin. Basically they start to open too early and achieve full actuation too late. Thus, the possibility of suction entrapment injury remains.
It is against this background that the significant improvements and advancements of the present invention have taken place.